When manufacturing packaging and packaging material for products which need to be packaged under more or less sterile conditions, the packaging must be sterilized before the products are positioned or wrapped in the packaging. Examples of such products are food products and pharmaceuticals, in particular liquid pharmaceuticals.
It is known to sterilize packaging or packaging material for such products by directing a beam of ionizing radiation, e.g. an electron beam or a beam of gamma rays towards the packaging material. This is, e.g. described in WO 02/072157, U.S. Pat. No. 3,780,308 and U.S. Pat. No. 4,035,981. However, such a beam of ionizing radiation may cause chemical reactions in the packaging material. This may result in the formation of compounds or substances which are reactive with respect to proteins. Thus, if the product is positioned in the packaging immediately after the sterilization, these compounds or substances may react with proteins which are present in the product, thereby leading to undesired alterations of the product. In case the product is a food product, such alterations may cause the taste of the product to be altered in an undesired manner. In case the product is a pharmaceutical the reactive compounds or substances may cause alterations in an active component of the pharmaceutical, and this may lead to alterations in the therapeutic effect of the pharmaceutical, possibly in such a manner that the therapeutic effect of the pharmaceutical may be unknown and even varying from one package to another. This is very undesirable.
The situation described above is in particular a problem when the packaging material is or comprises a polymer material. In this case irradiation of the material using ionizing radiation may cause carbon-carbon bonds and/or carbon-hydrogen bonds of the polymer material to break, and/or it may cause pieces of polymer (e.g. comprising 3-6 carbon atoms) to become detached from the original polymer chain. The result may be the formation of free radicals or smaller molecules which may potentially migrate from the irradiated packaging material into the product or substance being stored in the packaging material, and/or the formation of compounds comprising hydrocarbon and oxygen, e.g. aldehydes, ketones, alcohols or carboxylic acid. All of the compounds or substances mentioned above are very reactive with respect to proteins. Furthermore, once they have been formed in the polymer material, there is a risk that they will migrate into the product being contained in the packaging, and thereby react with proteins present in the product, leading to the undesired effects described above.
One way to address this problem is to allow a time period to lapse from the irradiation of the packaging material until the product is positioned or wrapped in the packaging. The lapsed time period should be sufficient to ensure that the undesired compounds or substances react spontaneously, e.g. with ambient air molecules, or evaporates from the packaging material. Such a process is, e.g., described in WO 02/072157, disclosing a method of producing sterile prefilled syringe bodies. The syringe bodies are sterilized using a beam of ionizing radiation and transferred to a sterile environment, and the syringe bodies are maintained in a sterilized condition as they are transferred to the sterile environment. A fluid substance is provided and introduced into the syringe body while the syringe body is within the sterile environment. The syringe bodies are filled within 5 days of the irradiation, but it is preferred that they are filled after approximately 15 minutes.
It is a disadvantage that it is necessary to allow a time period to lapse between irradiation of the packaging material and positioning the product in the packaging, because it adds to the total processing time. In particular, it adds to the time the packaging needs to be maintained in a sterile environment. This causes requirements to the sterile environment in terms of available storage space. Furthermore, the sterile environment needs to be positioned in immediate vicinity of the irradiation station, or the transport from the irradiation station to the sterile environment must be carried out very carefully and under strict sterile conditions. Otherwise there is a risk that the sterilized packaging material will be contaminated before the product can be positioned in the packaging and the packaging is sealed. This introduces the risk that the product is in fact not positioned in a sterile packaging, and the product may therefore also be contaminated, possibly introducing a health risk to a user.
WO 2004/110869 discloses a method and a device for ventilating a device for electron beam irradiation of a web. Irradiation of the web is performed while the web is moved through an irradiation chamber. While the web is irradiated a flow of gaseous fluid is created in the irradiation chamber in a direction opposite to the moving direction of the web. Thereby ozone created in the air surrounding the web is removed. The method and the device disclosed in WO 2004/110869 do not solve the problems described above, since the flow of gaseous fluid has no, or only a limited, effect on protein reactive substances or compounds which may be formed in the packaging material during irradiation. Furthermore, the flow of gaseous fluid is moved along the web during the irradiation, and protein reactive substances or compound formed at the end of the irradiation process will therefore not be affected by the flow of gaseous fluid.
JP 11084100 discloses a device for sterilizing objects. The objects are moved past an irradiation station, and then into an aseptic room container in order to prevent the objects from being contaminated again after irradiation. The surface of the aseptic room container may be sterilized by means of heating. In order to sterilize the surface of the aseptic room container by means of heating, a relatively high temperature, such as above 300° C., must be provided in the aseptic room container, and the device disclosed in JP 11084100 will therefore not be suitable for sterilizing packaging material made from a polymer material.
Packaging and packaging materials which are suitable for storing liquid solutions or suspensions, such as medicaments are disclosed in WO 2005/000580 and WO 2005/061222, which are hereby incorporated by reference.